X‐Ray Investigation of Boron‐ and Germanium‐Doped Silicon Epitaxial Layers

The lattice strain in highly boron‐doped, highly germanium‐doped, and simultaneously boron‐and‐germanium‐doped epitaxial layers was investigated by means of x‐ray techniques. The lattice‐contraction coefficient was determined for both impurities, and was found to be 5 × 10 − 24 cm 3 / atom for boron and − 6.2 × 10 − 25 cm 3 / atom for germanium doping. A simple linear superposition of calculated or experimentally determined lattice‐contraction coefficients obtained for layers doped with boron vs. those doped with germanium does not yield satisfactory results in estimating the germanium concentration necessary for strain compensation in highly boron‐doped layers. Strain‐compensated dislocation‐free epitaxial layers were fabricated with a boron concentration of 1 × 10 20 atom / cm 3 , using a germanium concentration of 1 × 10 21 atom / cm 3 .